Does seed migration increase the risk of second malignancies in prostate cancer patients treated with I-125 loose seeds brachytherapy?

Publication date: Available online 28 December 2017
Source:International Journal of Radiation Oncology*Biology*Physics
Author(s): Éric Vigneault, Kevin Martell, Daniel Taussky, Siraj Husain, Guila Delouya, Khaly Mbodji, Julie Piotte, Sindy Magnan, Philippe Després, Marie-Claude Lavallée, Sylviane Aubin, Luc Beaulieu, William Foster, André-Guy Martin
PurposeTo evaluate the risk of second malignancies after migration of seeds (MS) in prostate cancer patients treated with I-125 loose seeds brachytherapy.Materials and MethodsData from 2802 prostate cancer patients treated with I-125 loose seeds brachytherapy in three Canadian centres were reviewed. After seeds implant, all patients underwent post implant pelvic radiography and CT scan for post implant dosimetry. These images were used to assess if seed migration occurred. The incidence of second malignancies was determined through the review of patient's chart. The 7- and 10-year cumulative incidences of second malignancies and their 95% confidence intervals were calculated. Fine and Gray competing risk regression analysis was used to assess the factors associated with the development of a second malignancies.ResultsMean age and median follow-up was 63.5 years and 74 (range 12-246) months. MS occurred in 263 of 2802 patients (9.4%). Second malignancies occurred in 87 (3.1%) patients for the entire cohort and was not different between patients who experienced MS (9, 3.4%) or not (78, 3.1%) (p=0.755). The 7-year cumulative incidence rates of second malignancies were 2.95% (1.20%-6.00%) (with MS) vs. 2.82% (2.10%-3.70%) (without MS) (p=0.756). The corresponding values at 10-years were 6.16% (2.20%-12.3%) vs.4.51% (3.20%-5.50%) (p=0.570). MS did not appear to be a significant predictor factor for second malignancies development (adjusted HR 1.27 [95%CI, 0.63-2.55]; p=0.510). In both model, only advanced age was significantly associated with second malignancies development.ConclusionThese results did not show an increased risk of second malignancies associated with MS after I-125 loose seeds brachytherapy for prostate cancer patients. Longer follow-up and more events are required to better correlate MS and second malignancies.



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